« Il s’agit d’à quoi je ressemble. » sounds very odd, as you say.

The following is acceptable, but there are other ways to express it as well:

Il s’agit de ce à quoi je ressemble.

Other similar options:

Il s’agit de mon apparence personnelle.
C’est une question de mon apparence personnelle.
Çela a à voir avec ce à quoi je ressemble.

The following translations are found in the dictionary “reverso”.

Now it’s all about believing. → Maintenant, tout est dans la foi.

See, it’s all about sizing up your opponent. → Tout est dans l’évaluation de ton ennemi.

She says it’s all about the case, but it’s not. → Elle dit qu’il s’agit de l’affaire mais ce n’est pas le cas.

For me, it’s all about justice. → Pour moi, il s’agit de justice.

Apparently it’s all about the landing. → Apparemment, tout est dans l’atterrissage.

Look, it’s all about appearance. → Regardez, tout n’est qu’apparence.

On a grammatical note, let’s first point out that there is a way to combine “s’agir de” and “à quoi”. Here is an example:

S’agit-il de ce à quoi je pense ? (Is it what I think it is?)

However, in your case “s’agir de” wouldn’t match the “it’s all about”. You need a different phrase to express this. Here is one way to translate “it’s all about the way I look”, which should work in most contexts¹:

Ce qui importe c’est mon look².

or using variants :

Ce qui est important / c’est ce à quoi je ressemble.
La seule chose qui importe / c’est mon apparence.

But there are probably many more ways to phrase this in a given context.

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<sup>1. The way you look could be at stake, or something else that will depend on how you look.
2. Commonly used as a noun in French</sup>